1. Field of the Invention
The present invention relates to a zoom lens system for a compact camera, and in particular, relates to a zoom lens system having a wider angle-of-view at the short focal length extremity.
2. Description of the Related Art
Unlike a zoom lens system for a single lens reflex camera which requires space to be provided behind the photographing lens system in order to place a mirror, a zoom lens system of a compact camera does not require a long back focal distance. Accordingly, a zoom lens system for a compact camera generally employs a telephoto type lens system having a positive lens element and a negative lens element, in this order from the object; whereas a zoom lens system for a single lens reflex camera employs a retrofocus type lens system having a negative lens element and a positive lens element, in this order from the object.
When a zoom lens system is a two-lens-group arrangement, the number of lens elements can be reduced, and whereby size and weight reduction of a camera can be achieved, which is also advantageous for reducing production costs of the camera. Accordingly, it is common for a zoom lens system of a compact camera to employ a two-lens-group arrangement. On the other hand, in the case where the half angle-of-view is required to be more than 35.degree. and the zoom ratio is required to be about 2.8, a three-lens-group arrangement is predominantly employed in order to maintain optimum optical performance. However, if a three-lens-group zoom lens system is employed, the diameter of the front-most lens element in the front lens group has to be increased, and the number of lens elements is also increased, both of which adversely influence miniaturization of the camera. Furthermore, due to the complexity of a three-lens-group arrangement, adjustment work thereof is difficult.